JP3526174B2 - Semiconductor exposure apparatus and device manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor exposure apparatus for exposing and transferring a fine pattern of a semiconductor integrated circuit drawn on a mask membrane onto a substrate such as a wafer, and more particularly to bringing the mask membrane and the substrate close to each other at a minute interval. The present invention relates to a proximity type semiconductor exposure apparatus and a device manufacturing method for performing exposure by exposure.

[0002]

2. Description of the Related Art An X-ray exposure apparatus is a typical exposure apparatus of the proximity type which exposes a mask membrane and a substrate such as a wafer close to each other at a minute interval.
For example, an X-ray exposure apparatus using an SR light source is disclosed in Japanese Patent Laid-Open No. 2-1.
It is described in Japanese Patent Publication No. 00311.

FIG. 7 shows a general structure of an X-ray exposure apparatus of this type. In FIG. 7, a mask 101 having a mask membrane 103 on which an absorber pattern is drawn is a mask chuck 1 supported by a mask chuck base 104.
It is sucked and held by 02 and positioned with respect to the X-ray optical path. The wafer 105, which is a substrate arranged facing the mask 101 and close to the mask 101, is held by the wafer chuck 106.
The wafer chuck 1 is mounted on the fine movement stage 107 used for aligning the wafer 105 with respect to the wafer chuck 1.
06 and the fine movement stage 107 are used for movement between shots in order to stepwise move a plurality of exposure field angles of the wafer 105 to the X-ray irradiation area.
The guide of the coarse movement stage 108 is fixed to the stage base 109.

In the X-ray exposure apparatus, the pattern on the mask membrane 103 is generally formed on the wafer 10.
5 is repeatedly exposed a plurality of times by the step-and-repeat method, and the mask membrane 103 and the wafer 1 are exposed.
The exposure is performed by a proximity method in which the No. 05 is exposed at a minute interval of 10 to 50 μm. The mask membrane on which the absorber pattern is formed is a thin film having a thickness of about 2 μm.

In such a conventional X-ray exposure apparatus,
The procedure of performing exposure by die-by-die alignment will be described. (1) The coarse movement stage 108 is driven so that the portion of the wafer 105 where the nth shot is exposed is below the mask membrane 103.

(2) The fine movement stage 107 drives the wafer 105 to a gap for exposure.

(3) Mask 1 by fine movement stage 107
After aligning 01 with the wafer 105, exposure is performed.

(4) Retreat to the gap at the time of step.

Hereinafter, the steps (1) to (4) are repeated,
The wafer 105 is exposed for a predetermined number of shots.

[0010]

By the way, in the conventional proximity type exposure apparatus as described above, the mask membrane is thin with a thin film of about 2 μm, and the mask and the wafer are close to each other. It is assumed that the mask membrane is deformed during the stage movement such as the gap setting or the step movement between exposure shots. Therefore, the following problems are concerned.

(1) Gap measurement cannot be appropriately and accurately performed due to deformation of the mask membrane.

(2) Positioning accuracy deteriorates due to displacement in the in-plane direction due to deformation in the out-of-plane direction.

(3) Transfer accuracy (image performance) deteriorates.

In order to solve these problems, for example, a method of exposing after setting a sufficient time after setting the exposure gap, or performing the exposure by adjusting the gap, or driving the stage so that the mask membrane is not deformed Although it is conceivable that the method is performed slowly, the throughput will be reduced by these methods.

Further, by adjusting the gap between the mask and the wafer based on the information about the gap between the mask and the wafer, the mask is moved stepwise so as to suppress the deformation of the mask membrane during the step movement, thereby reducing the throughput and the alignment accuracy. The applicant has also proposed a method for improving the exposure accuracy. As described above, it is important to optimally control the gap between the mask and the wafer in order to suppress the deformation of the mask membrane, but the height position of the mask is usually measured in the exposure apparatus without measurement. Measurement values measured separately in advance are used as data for each mask, and the gap between the mask and the wafer is calculated using this data for each mask. There was a slight problem with sex.

Therefore, the present invention has been made in view of the above-mentioned unsolved problems of the prior art, and highly accurately measures information on the height position of a mask membrane and a substrate such as a wafer on the apparatus. By improving the accuracy of the gap control, the deformation of the mask membrane is suppressed, the alignment accuracy of the mask and the substrate and the transfer accuracy are further improved, and the measurement means for measuring the height position of the mask membrane and the substrate is provided. An object of the present invention is to provide a semiconductor exposure apparatus with higher reliability by performing comparison / calibration on the apparatus, and to provide a device manufacturing method capable of manufacturing semiconductor devices more efficiently.

[0017]

In order to achieve the above object, a semiconductor exposure apparatus of the present invention is a semiconductor exposure apparatus for exposing a mask having an absorber pattern on a mask membrane and a substrate at a minute interval. The first measuring means for measuring the distance between the mask membrane and the device reference surface, the second measuring means fixed to the device for measuring the height position of the substrate, and the first and second measuring means. The distance between the mask and the substrate is measured based on the measurement result , and at least one of the mask and the substrate is driven.
Have a control means, said second measuring means, said device reference
The surface can be measured and is measured by the second measuring means.
Using the measurement result of the device reference plane,
It is characterized in that the measured value of the distance between the substrates is calibrated .

[0018]

Further, in the semiconductor exposure apparatus of the present invention, the second measuring means can be composed of a plurality of minute displacement gauges arranged around the mask and fixed to the apparatus.
Alternatively, it can be configured with a single micro-displacement meter that is fixed to the device and can measure the height of the entire surface of the substrate.

[0020]

Further, the device manufacturing method of the present invention is characterized in that a device is manufactured using the semiconductor exposure apparatus according to any one of claims 1 to 5.

[0022]

In the X-ray exposure apparatus, the height position of the mask membrane is directly measured from the distance between the mask membrane and the apparatus reference plane provided on the apparatus , and the height position of the substrate is measured by the displacement gauge fixed to the apparatus. , without being affected by the deformation of the mask membrane, as well as to as to be able to measure the substrate exposed surface, so as to optimally control the gap therebetween by driving at least one of the mask or substrate on the basis of their measurement results In addition, the height positions of the mask membrane and the substrate can be measured with high accuracy in a state where they are installed in the device, and the deformation of the mask membrane when the stage is driven can be suppressed to a predetermined value or less. It is possible to prevent contact and damage between the mask and the substrate, and further improve the accuracy when aligning the mask and the substrate or during exposure.

Further, the substrate height can be measured in real time by a plurality of displacement gauges fixed around the mask, and the entire surface of the substrate can be measured in advance by one displacement gauge. You can also

[0024] Then, as capable of carrying out comparison and calibration of the measuring means for measuring a height position of the mask membrane and the substrate, respectively (calibration) on the device, and a high strong reliable X-ray exposure apparatus to change over time can do.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a partial sectional view schematically showing the construction of an X-ray exposure apparatus according to the first embodiment of the present invention. The X-ray exposure apparatus according to the first embodiment of the present invention will be described below with reference to FIG.

The mask 1 having the mask membrane 2 on which the absorber pattern is formed is suction-held by the mask chuck 3 and mounted on the mask stage 4. The mask stage 4 is attached to the mask stage base 5 and is configured so that the mask 1 can be positioned in the Z tilt direction. Further, the wafer 6 which is a substrate arranged to face the mask 1 is a wafer chuck 7
The wafer chuck 7 is mounted on a fine movement stage 8 used for aligning the mask 1 and the wafer 6 in the six axial directions (X, Y, Z directions and rotational directions with respect to the respective axes). The fine movement stage 7 and the fine movement stage 8 are mounted on a coarse movement stage 9 which is held so as to be movable in the X-axis and Y-axis directions with respect to the coarse movement stage base 10. Thus, the fine movement stage 8 supports the wafer chuck 7 that holds the wafer 6 by suction, and
It is provided so as to be movable in each of the 6 axis directions on the coarse movement stage 9. By moving the fine movement stage 8, the wafer 6 can be finally positioned with respect to the mask 1, and by moving in the Z axis direction. The distance between the mask 1 and the wafer 6 can be adjusted. The coarse movement stage 9 moves the wafer 6 between shots, and the coarse movement stage base 10 for fixing the guide of the coarse movement stage 9 is mechanically connected to the mask stage base 5.

A target (apparatus reference plane) 11 installed on the coarse movement stage 9 moves along with the coarse movement stage 9 by scanning the coarse movement stage 9, and the main exposure apparatus parallel to the coarse movement stage running surface. To form a virtual reference plane.

A plurality of minute displacement gauges 12 for measuring the height of the wafer surface in a non-contact manner are arranged around the mask stage 4 and fixed to the mask stage base 5, and at least three pieces are provided to obtain surface information of the wafer. (Note that only two are shown in the figure). Then, as the non-contact micro-displacement meter 12, for example, a non-contact micro-measuring device capable of non-contact measurement of the height of the wafer, such as a device that measures a reflected light with a laser and a device that measures a reflected light is used. .

A plurality of well-known alignment scopes 13 are mounted on the mask stage base 5, and the alignment scope 13 includes the mask membrane 2 and the wafer 6.
Of the alignment marks (not shown) provided on the exposed surfaces of the mask 1 and the exposed surface of the mask 11 and the target 11 or the wafer 6, respectively. At least three pieces are provided to obtain the surface information of
Only two are shown in the figure. ).

Numeral 14 is a first arithmetic means for obtaining an approximate surface of the mask membrane 2 based on the measurement results of at least three alignment scopes 13, and numeral 15 is a measurement result of at least three non-contact displacement gauges 12. Is a second calculation means for obtaining an approximate surface of the exposure surface of the wafer 6 from
Reference numeral 6 indicates the mask stage 4 or the fine movement stage 8 based on the calculation result of the first calculating means 14 or the second calculating means 15.
It is a control means for controlling.

A method for controlling the gap (gap) between the exposure surface of the mask membrane 2 and the wafer 6 in the X-ray exposure apparatus of the present embodiment configured as described above will be described with reference to FIG. explain.

(1) First, as shown in FIG.
After chucking the mask 1 on the mask chuck 3,
The target 11 is moved below the first alignment scope 13a by the coarse movement stage 9, and the distance between the target 11 and the mask membrane 2 is measured (this distance is G
a)). Then, the target 11 is moved to move the second and third alignment scopes 13b and 13c.
The same measurement is performed in (note that 13c is not shown) (the respective intervals are Gb and Gc).

(2) Then, the measurement results of these alignment scopes 13 are sent to the first calculation means 14, and the first calculation means 14 is formed by the surface of the target 11 based on these measurement results. The approximate surface of the mask membrane 2 with respect to the virtual reference surface is obtained, and the mask stage 4 is appropriately driven via the control means 16 so that the approximate surface is set at a predetermined height with respect to the virtual reference surface.
Thus, the mask membrane 2 is installed at a predetermined height with respect to the virtual reference plane, as shown in FIG.

Next, exposure and gap control by die-by-die alignment will be described.

(1) The wafer 6 is chucked on the wafer chuck 7.

(2) Then, the wafer 6 is moved to the coarse movement stage 9
Is moved to the position of the first shot by, and a plurality of (three in this embodiment) non-contact displacement gauges 12 (12
a, 12b and 12c) (not shown) measure the height of the surface of each wafer 6, and the measurement results are the second
Is sent to the calculation means 15. The second calculation means 15 obtains the approximate surface of the wafer 6 based on the measurement results.
Then, the control means 16 compares the approximate surface of the wafer 6 with the approximate surface of the mask membrane 2 previously obtained, and drives the fine movement stage 8 in the Z direction, whereby the mask membrane 2 and the wafer 6 are moved. The interval (gap) is set to a predetermined exposure gap (see (c) in FIG. 2).

(3) After that, the alignment scope 13
Using, the mask membrane 2 and the wafer 6 are aligned and exposed.

(4) After the exposure, the wafer 6 is moved by the coarse movement stage 9 to the position of the second shot without changing the gap between the mask 1 and the wafer 6. At this time,
The surface of the wafer 6 is measured by the three non-contact displacement gauges 12 (12a, 12b, 12c), and the approximate surface of the wafer 6 is obtained by the second calculation means 15 based on the measurement results, and the approximation of the mask membrane 2 is performed. The coarse movement stage 9 is driven while controlling the fine movement stage 8 by the control means 16 so that the gap between the surface and the approximate surface of the wafer 6 becomes a predetermined value, and the wafer 6
To the position of the second shot.

During this step movement, if the tilt amount of the wafer stage is large and the deformation amount of the wafer 6 is large on the approximate surface of the wafer 6 obtained by the at least three non-contact displacement gauges 12, the wafer 6 is moved. Mask 1
Therefore, the gap between the mask 1 and the wafer 6 is once widened, the wafer is moved to the next shot position, and the gap is adjusted at that position in the same sequence as described above and exposure is started. You can also do so.

(5) Then, after the wafer 6 is moved to the position of the second shot, the wafer is aligned with the alignment scope and then exposed.

By repeating the above operation, the wafer 6 can be exposed for a predetermined number of shots.

As described above, in this embodiment, the height positions of the mask membrane and the wafer can be measured with high accuracy in a state of being installed in the exposure apparatus, and the mask membrane of the mask membrane when the stage is driven can be measured. The deformation can be suppressed to a predetermined value or less, contact and damage between the mask and the wafer can be prevented, and the accuracy at the time of aligning the mask and the wafer or at the time of exposure can be improved. Further, the height of the wafer can be measured and the gap can be controlled in real time, and an exposure apparatus having an excellent processing speed can be realized.

The method of this embodiment described above is also effective for exposure of global alignment. Further, in this embodiment, the height of the mask is adjusted when the mask is installed. However, for example, when the stroke of the fine movement stage on the wafer side has a sufficient margin, the measured mask membrane and wafer position information Based on the above, all the gap adjustment may be performed on the wafer side. Further, the target 11 may be installed on the wafer chuck 7, and in this case, the fine movement stage 8 should always be kept at a fixed position for measurement.

[0045] Furthermore, the non-contact displacement gauge 12, as well as measurement of the exposure surface of the wafer 6, the height is also measurable configured to your Kukoto target 11, the measurement value by the alignment scope 13 on device and non The measurement values of the contact displacement meter 12 can be compared and calibrated (see FIG. 3).
The procedure will be described below.

(1) Target 1 by coarse movement stage 9
1 under the first alignment scope 13a,
The distance Ga between the target 11 and the mask membrane 2 is measured. Further, in the second and third alignment scopes 13b and 13c as well, the respective gaps Gb,
Gc is measured.

(2) Then, the target 11 is moved below the non-contact displacement gauge 12a by the coarse movement stage 9,
The height Da of the target 11 is measured. The other non-contact displacement gauges 12b and 12c similarly measure the heights Db and Dc of the respective targets 11.

(3) In the third calculating means 17, the measurement result (Ga, Gb, Gc) of the alignment scope 13
By comparing the measurement results (Da, Db, Dc) of the non-contact displacement meter 12 with the non-contact displacement meter 12 (12a, 12b, 1) via the virtual reference plane formed by the target 11.
2c) and the alignment scope 13 (13a, 13
It is possible to compare and calibrate the measured values of b and 13c).

It should be noted that this calibration may be carried out as necessary, and may be carried out, for example, every time the apparatus is started up.

Since the alignment scope and the non-contact displacement meter can be compared and calibrated on the apparatus as described above, it is possible to obtain an X-ray exposure apparatus which is resistant to aging and highly reliable.

Next, an X-ray exposure apparatus according to the second embodiment of the present invention will be described. FIG. 4 is a partial cross-sectional view schematically showing the configuration of the X-ray exposure apparatus according to the second embodiment of the present invention,
In the present embodiment, the arrangement of the non-contact displacement gauge is different from that of the first embodiment, and one non-contact displacement gauge 22 is fixed to the mask stage base 5 to scan the coarse movement stage 9. , The entire surface of the wafer 6 and the target 11
It is configured so that the height of can be measured. Other configurations are the same as those of the first embodiment, the same members are designated by the same reference numerals, and detailed description thereof will be omitted.

A method of controlling the gap (gap) between the exposure surface of the mask membrane 2 and the wafer 6 in this embodiment will be described according to its operation. The mask is installed in the same manner as in the first embodiment. The plurality of alignment scopes 13 measure the distance between the mask membrane 2 of the mask 1 chucked on the mask chuck 3 and the target 11 provided on the coarse movement stage 9, and the first calculation means 14 determines the distance between them. The approximate surface of the mask membrane 2 is obtained by using the control means 16 so that the approximate surface is set at a predetermined height with respect to the virtual reference surface.
The mask stage 4 is driven to set the mask membrane 2 at a predetermined height with respect to the virtual reference plane.

Next, exposure and gap control will be described.

(1) The wafer 6 is chucked on the wafer chuck 7.

(2) After that, the coarse movement stage 9 is scanned and moved so that the entire surface of the wafer 6 faces one non-contact displacement meter 22 fixed to the mask stage base 5. The non-contact displacement meter 22 measures the height of the entire surface of the wafer 6, and based on the measurement result, the second calculation means 15 maps the height of the entire wafer to obtain an approximate surface. Then, the control means 16 compares the mapped approximate surface of the wafer 6 with the previously calculated approximate surface of the mask membrane 2 to determine the approximate surface and the gap between the mask membrane 2 and the wafer 6 with the stage traveling surface as a reference. Ask.

(3) Thereafter, the control means 1 is arranged so that the distance between the mask membrane 2 and the wafer 6 becomes a predetermined gap.
6, the coarse movement stage 9 is driven while controlling the fine movement stage 8 to perform exposure or global measurement.

As described above, in this embodiment, the height of the entire surface of the wafer 6 is measured by the non-contact displacement meter 22 and the height of the entire wafer is mapped in advance, so that the stage drive path and the mask membrane are And the wafer gap adjustment can be set in advance, it is not necessary to adjust the gap at each shot position, the throughput can be improved, and the wafer height is finely measured over the entire wafer surface. Therefore, the accuracy of the wafer height measurement and the gap control can be improved.

Also in this embodiment, like the first embodiment, when the stroke of the fine movement stage on the wafer side has a sufficient margin, all the gap adjustment is performed on the wafer based on the measured mask position information. You may do it on your side.
Further, the target 11 may be installed on the wafer chuck 7, and in this case, the fine movement stage 8 should always be kept at a fixed position for measurement.

The calibration of the measuring means in the second embodiment can be performed in the same manner as in the first embodiment.

Next, an embodiment of a device manufacturing method using the above-described exposure apparatus will be described.

FIG. 5 shows minute devices (semiconductor chips such as IC and LSI, liquid crystal panel, CCD, thin film magnetic head,
The flow of manufacturing a micromachine etc. is shown. Step 1
In (Circuit design), the device pattern is designed. In step 2 (mask manufacturing), a mask having the designed pattern is manufactured. On the other hand, step 3 (wafer manufacture)
Then, a wafer is manufactured using a material such as silicon or glass. Step 4 (wafer process) is called a pre-process,
An actual circuit is formed on the wafer by the lithography technique using the mask and the wafer prepared above. The next step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip by using the wafer manufactured in step 4, such as an assembly process (dicing, bonding), a packaging process (chip encapsulation), and the like. including. In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. Through these steps, the semiconductor device is completed and shipped (step 7).

FIG. 6 shows a detailed flow of the wafer process. In step 11 (oxidation), the surface of the wafer is oxidized. In step 12 (CVD), an insulating film is formed on the wafer surface. In step 13 (electrode formation), electrodes are formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted in the wafer. Step 1
In 5 (resist processing), a photosensitive agent is applied to the wafer. In step 16 (exposure), the circuit pattern of the mask is printed and exposed on the wafer by the exposure apparatus having the alignment apparatus described above. In step 17 (development), the exposed wafer is developed. In step 18 (etching), parts other than the developed resist image are removed. Step 19
In (resist stripping), the unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

By using the manufacturing method of this embodiment, it is possible to manufacture a highly integrated device, which has been difficult to manufacture in the past, at a low cost.

[0064]

Since the present invention is configured as described above, it becomes possible to measure the height positions of the mask membrane and the substrate with high accuracy in a state where the mask membrane and the substrate are installed in the apparatus, and the mask when the stage is driven. It is possible to suppress the deformation of the membrane to a predetermined value or less, prevent contact and damage between the mask and the substrate, and further improve accuracy when aligning the mask and the substrate or during exposure.

Furthermore, since the first measuring means and the second measuring means can be compared and calibrated on the apparatus, it is possible to obtain an exposure apparatus which is resistant to aging and highly reliable.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view schematically showing a configuration of an X-ray exposure apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a gap control procedure of the X-ray exposure apparatus according to the first embodiment of the present invention in process order.

FIG. 3 is a partial cross-sectional view illustrating a comparison / calibration method of measuring means in the X-ray exposure apparatus according to the first embodiment of the present invention.

FIG. 4 is a partial sectional view schematically showing a configuration of an X-ray exposure apparatus according to a second embodiment of the present invention.

FIG. 5 is a flowchart showing manufacturing steps of a semiconductor device.

FIG. 6 is a flowchart showing details of a wafer process.

FIG. 7 is a partial cross-sectional view schematically showing the configuration of a conventional X-ray exposure apparatus.

[Explanation of symbols]

1 mask 2 mask membrane 3 mask chuck 4 mask stage 5 mask stage base 6 wafer (substrate) 7 wafer chuck 7 8 fine movement stage 9 coarse movement stage 11 target 12 (12a, 12b, 12c) non-contact (small) displacement gauge 13 ( 13a, 13b, 13c) Alignment scope 14 First calculating means 15 Second calculating means 16 Control means 17 Third calculating means 22 Non-contact displacement meter

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A 64-21920 (JP, A) JP-A 59-17247 (JP, A) JP-A 58-103136 (JP, A) JP-A 57- 204547 (JP, A) JP 3-253917 (JP, A) JP 3-185810 (JP, A) JP 3-185808 (JP, A) JP 2-230714 (JP, A) JP-A-1-285802 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/027 G03F 7/20 G03F 9/00

Claims (4)

(57) [Claims] 1. A semiconductor exposure apparatus that exposes a mask having an absorber pattern on a mask membrane and a substrate in close proximity to each other with a minute distance, and measuring a distance between the mask membrane and a device reference surface .
Based on the measurement results of the first measuring means and the second measuring means fixed to the device to measure the height position of the substrate.
Have a control means for driving at least one of the mask and the substrate by measuring the distance between the substrate and the mask
However, the second measuring means can measure the device reference plane.
The device reference measured by the second measuring means
The measurement result of the surface is used to determine the distance between the mask and the substrate.
A semiconductor exposure apparatus characterized by calibrating measured values . Wherein said second measuring means semiconductor exposure apparatus according to claim 1, characterized in that the plurality of micro displacement meter fixed on the device is placed around the mask. 3. The semiconductor exposure apparatus according to claim 1, wherein the second measuring means is one minute displacement meter fixed to the apparatus and capable of measuring the height of the entire surface of the substrate. 4. A device manufacturing method characterized by manufacturing a device using the semiconductor exposure apparatus according to any one of claims 1 to 3.